Field of the Invention
The presently disclosed subject matter relates to an inkjet recording apparatus and a control method therefor, particularly to an inkjet recording apparatus provided with a wetting device for wetting a portion around a nozzle of an inkjet head, and a control method therefor.
Description of the Related Art
There is disclosed in Japanese Patent Application Laid-Open No. 2012-158018 a liquid ejection apparatus in which an ejection space facing a plurality of ejection openings of an liquid ejection head is brought into a sealed state by means of a cap so as to be humidified (in paragraphs [0054] and [0058] in Japanese Patent Application Laid-Open No. 2012-158018). In Japanese Patent Application Laid-Open No. 2012-158018, a humidity in the ejection space is controlled to be a predetermined humidity by a temperature of humid air, a supply amount of the humid air per unit time, or the like. There is described in the above document that this predetermined humidity is a humidity when a viscosity of ink in the head is within a proper range in terms of an image quality, and only a lower limit value of the humidity, that is, a humidity corresponding to an upper limit value of the viscosity may be defined.
There is disclosed in Japanese Patent Application Laid-Open No. 2003-145783 an ink jet unit in which evaporation of a solvent in ink can be reduced or prevented by bringing a solvent vapor concentration in a space outside of a nozzle close to a solvent vapor concentration inside the nozzle in the vicinity of a meniscus surface or by providing an environment having at least a relative humidity equal to or more than 60% RH (in a paragraph [0014] in Japanese Patent Application Laid-Open No. 2003-145783). There is described in Japanese Patent Application Laid-Open No. 2003-145783 that if a superabsorbent polymer in a form of sheet having a thickness of 0.1 mm made of a hydrolytic fibrous superabsorbent polymer of acrylic fibers (Lanseal (registered trademark) from Japan Exlan Co., LTD.) is used for a holder of an inkjet head, the relative humidity of the space in the vicinity of the nozzle can be set to 65% RH to 76% RH in a winter environment and 76% RH to 85% RH in a summer environment due to an action of moisture transpiration from this superabsorbent polymer (in paragraphs [0024] and [0025] in Japanese Patent Application Laid-Open No. 2003-145783).